FreeBSD/Linux Kernel Cross Reference
sys/dev/uart/uart_core.c

     /*-
      * Copyright (c) 2003 Marcel Moolenaar
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      *
      * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/8.4/sys/dev/uart/uart_core.c 235121 2012-05-07 07:04:41Z marius $");
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/bus.h>
    #include <sys/conf.h>
    #include <sys/cons.h>
    #include <sys/fcntl.h>
    #include <sys/interrupt.h>
    #include <sys/kdb.h>
    #include <sys/kernel.h>
    #include <sys/malloc.h>
    #include <sys/queue.h>
    #include <sys/reboot.h>
    #include <machine/bus.h>
    #include <sys/rman.h>
    #include <sys/termios.h>
    #include <machine/resource.h>
    #include <machine/stdarg.h>
    
    #include <dev/uart/uart.h>
    #include <dev/uart/uart_bus.h>
    #include <dev/uart/uart_cpu.h>
    
    #include "uart_if.h"
    
    devclass_t uart_devclass;
    char uart_driver_name[] = "uart";
    
    SLIST_HEAD(uart_devinfo_list, uart_devinfo) uart_sysdevs =
        SLIST_HEAD_INITIALIZER(uart_sysdevs);
    
    MALLOC_DEFINE(M_UART, "UART", "UART driver");
    
    void
    uart_add_sysdev(struct uart_devinfo *di)
    {
            SLIST_INSERT_HEAD(&uart_sysdevs, di, next);
    }
    
    const char *
    uart_getname(struct uart_class *uc)
    {
            return ((uc != NULL) ? uc->name : NULL);
    }
    
    struct uart_ops *
    uart_getops(struct uart_class *uc)
    {
            return ((uc != NULL) ? uc->uc_ops : NULL);
    }
    
    int
    uart_getrange(struct uart_class *uc)
    {
            return ((uc != NULL) ? uc->uc_range : 0);
    }
    
    /*
     * Schedule a soft interrupt. We do this on the 0 to !0 transition
     * of the TTY pending interrupt status.
     */
    void
    uart_sched_softih(struct uart_softc *sc, uint32_t ipend)
    {
            uint32_t new, old;
    
            do {
                    old = sc->sc_ttypend;
                    new = old | ipend;
            } while (!atomic_cmpset_32(&sc->sc_ttypend, old, new));
    
           if ((old & SER_INT_MASK) == 0)
                   swi_sched(sc->sc_softih, 0);
   }
   
   /*
    * A break condition has been detected. We treat the break condition as
    * a special case that should not happen during normal operation. When
    * the break condition is to be passed to higher levels in the form of
    * a NUL character, we really want the break to be in the right place in
    * the input stream. The overhead to achieve that is not in relation to
    * the exceptional nature of the break condition, so we permit ourselves
    * to be sloppy.
    */
   static __inline int
   uart_intr_break(void *arg)
   {
           struct uart_softc *sc = arg;
   
   #if defined(KDB)
           if (sc->sc_sysdev != NULL && sc->sc_sysdev->type == UART_DEV_CONSOLE) {
                   if (kdb_break())
                           return (0);
           }
   #endif
           if (sc->sc_opened)
                   uart_sched_softih(sc, SER_INT_BREAK);
           return (0);
   }
   
   /*
    * Handle a receiver overrun situation. We lost at least 1 byte in the
    * input stream and it's our job to contain the situation. We grab as
    * much of the data we can, but otherwise flush the receiver FIFO to
    * create some breathing room. The net effect is that we avoid the
    * overrun condition to happen for the next X characters, where X is
    * related to the FIFO size at the cost of loosing data right away.
    * So, instead of having multiple overrun interrupts in close proximity
    * to each other and possibly pessimizing UART interrupt latency for
    * other UARTs in a multiport configuration, we create a longer segment
    * of missing characters by freeing up the FIFO.
    * Each overrun condition is marked in the input buffer by a token. The
    * token represents the loss of at least one, but possible more bytes in
    * the input stream.
    */
   static __inline int
   uart_intr_overrun(void *arg)
   {
           struct uart_softc *sc = arg;
   
           if (sc->sc_opened) {
                   UART_RECEIVE(sc);
                   if (uart_rx_put(sc, UART_STAT_OVERRUN))
                           sc->sc_rxbuf[sc->sc_rxput] = UART_STAT_OVERRUN;
                   uart_sched_softih(sc, SER_INT_RXREADY);
           }
           UART_FLUSH(sc, UART_FLUSH_RECEIVER);
           return (0);
   }
   
   /*
    * Received data ready.
    */
   static __inline int
   uart_intr_rxready(void *arg)
   {
           struct uart_softc *sc = arg;
           int rxp;
   
           rxp = sc->sc_rxput;
           UART_RECEIVE(sc);
   #if defined(KDB)
           if (sc->sc_sysdev != NULL && sc->sc_sysdev->type == UART_DEV_CONSOLE) {
                   while (rxp != sc->sc_rxput) {
                           kdb_alt_break(sc->sc_rxbuf[rxp++], &sc->sc_altbrk);
                           if (rxp == sc->sc_rxbufsz)
                                   rxp = 0;
                   }
           }
   #endif
           if (sc->sc_opened)
                   uart_sched_softih(sc, SER_INT_RXREADY);
           else
                   sc->sc_rxput = sc->sc_rxget;    /* Ignore received data. */
           return (1);
   }
   
   /*
    * Line or modem status change (OOB signalling).
    * We pass the signals to the software interrupt handler for further
    * processing. Note that we merge the delta bits, but set the state
    * bits. This is to avoid loosing state transitions due to having more
    * than 1 hardware interrupt between software interrupts.
    */
   static __inline int
   uart_intr_sigchg(void *arg)
   {
           struct uart_softc *sc = arg;
           int new, old, sig;
   
           sig = UART_GETSIG(sc);
   
           if (sc->sc_pps.ppsparam.mode & PPS_CAPTUREBOTH) {
                   if (sig & UART_SIG_DPPS) {
                           pps_capture(&sc->sc_pps);
                           pps_event(&sc->sc_pps, (sig & UART_SIG_PPS) ?
                               PPS_CAPTUREASSERT : PPS_CAPTURECLEAR);
                   }
           }
   
           /*
            * Keep track of signal changes, even when the device is not
            * opened. This allows us to inform upper layers about a
            * possible loss of DCD and thus the existence of a (possibly)
            * different connection when we have DCD back, during the time
            * that the device was closed.
            */
           do {
                   old = sc->sc_ttypend;
                   new = old & ~SER_MASK_STATE;
                   new |= sig & SER_INT_SIGMASK;
           } while (!atomic_cmpset_32(&sc->sc_ttypend, old, new));
   
           if (sc->sc_opened)
                   uart_sched_softih(sc, SER_INT_SIGCHG);
           return (1);
   }
   
   /*
    * The transmitter can accept more data.
    */
   static __inline int
   uart_intr_txidle(void *arg)
   {
           struct uart_softc *sc = arg;
   
           if (sc->sc_txbusy) {
                   sc->sc_txbusy = 0;
                   uart_sched_softih(sc, SER_INT_TXIDLE);
           }
           return (0);
   }
   
   static int
   uart_intr(void *arg)
   {
           struct uart_softc *sc = arg;
           int flag = 0, ipend;
   
           while (!sc->sc_leaving && (ipend = UART_IPEND(sc)) != 0) {
                   flag = 1;
                   if (ipend & SER_INT_OVERRUN)
                           uart_intr_overrun(sc);
                   if (ipend & SER_INT_BREAK)
                           uart_intr_break(sc);
                   if (ipend & SER_INT_RXREADY)
                           uart_intr_rxready(sc);
                   if (ipend & SER_INT_SIGCHG)
                           uart_intr_sigchg(sc);
                   if (ipend & SER_INT_TXIDLE)
                           uart_intr_txidle(sc);           
           }
           return((flag)?FILTER_HANDLED:FILTER_STRAY);
   }
   
   serdev_intr_t *
   uart_bus_ihand(device_t dev, int ipend)
   {
   
           switch (ipend) {
           case SER_INT_BREAK:
                   return (uart_intr_break);
           case SER_INT_OVERRUN:
                   return (uart_intr_overrun);
           case SER_INT_RXREADY:
                   return (uart_intr_rxready);
           case SER_INT_SIGCHG:
                   return (uart_intr_sigchg);
           case SER_INT_TXIDLE:
                   return (uart_intr_txidle);
           }
           return (NULL);
   }
   
   int
   uart_bus_ipend(device_t dev)
   {
           struct uart_softc *sc;
   
           sc = device_get_softc(dev);
           return (UART_IPEND(sc));
   }
   
   int
   uart_bus_sysdev(device_t dev)
   {
           struct uart_softc *sc;
   
           sc = device_get_softc(dev);
           return ((sc->sc_sysdev != NULL) ? 1 : 0);
   }
   
   int
   uart_bus_probe(device_t dev, int regshft, int rclk, int rid, int chan)
   {
           struct uart_softc *sc;
           struct uart_devinfo *sysdev;
           int error;
   
           sc = device_get_softc(dev);
   
           /*
            * All uart_class references are weak. Check that the needed
            * class has been compiled-in. Fail if not.
            */
           if (sc->sc_class == NULL)
                   return (ENXIO);
   
           /*
            * Initialize the instance. Note that the instance (=softc) does
            * not necessarily match the hardware specific softc. We can't do
            * anything about it now, because we may not attach to the device.
            * Hardware drivers cannot use any of the class specific fields
            * while probing.
            */
           kobj_init((kobj_t)sc, (kobj_class_t)sc->sc_class);
           sc->sc_dev = dev;
           if (device_get_desc(dev) == NULL)
                   device_set_desc(dev, uart_getname(sc->sc_class));
   
           /*
            * Allocate the register resource. We assume that all UARTs have
            * a single register window in either I/O port space or memory
            * mapped I/O space. Any UART that needs multiple windows will
            * consequently not be supported by this driver as-is. We try I/O
            * port space first because that's the common case.
            */
           sc->sc_rrid = rid;
           sc->sc_rtype = SYS_RES_IOPORT;
           sc->sc_rres = bus_alloc_resource(dev, sc->sc_rtype, &sc->sc_rrid,
               0, ~0, uart_getrange(sc->sc_class), RF_ACTIVE);
           if (sc->sc_rres == NULL) {
                   sc->sc_rrid = rid;
                   sc->sc_rtype = SYS_RES_MEMORY;
                   sc->sc_rres = bus_alloc_resource(dev, sc->sc_rtype,
                       &sc->sc_rrid, 0, ~0, uart_getrange(sc->sc_class),
                       RF_ACTIVE);
                   if (sc->sc_rres == NULL)
                           return (ENXIO);
           }
   
           /*
            * Fill in the bus access structure and compare this device with
            * a possible console device and/or a debug port. We set the flags
            * in the softc so that the hardware dependent probe can adjust
            * accordingly. In general, you don't want to permanently disrupt
            * console I/O.
            */
           sc->sc_bas.bsh = rman_get_bushandle(sc->sc_rres);
           sc->sc_bas.bst = rman_get_bustag(sc->sc_rres);
           sc->sc_bas.chan = chan;
           sc->sc_bas.regshft = regshft;
           sc->sc_bas.rclk = (rclk == 0) ? sc->sc_class->uc_rclk : rclk;
   
           SLIST_FOREACH(sysdev, &uart_sysdevs, next) {
                   if (chan == sysdev->bas.chan &&
                       uart_cpu_eqres(&sc->sc_bas, &sysdev->bas)) {
                           /* XXX check if ops matches class. */
                           sc->sc_sysdev = sysdev;
                           sysdev->bas.rclk = sc->sc_bas.rclk;
                   }
           }
   
           error = UART_PROBE(sc);
           bus_release_resource(dev, sc->sc_rtype, sc->sc_rrid, sc->sc_rres);
           return ((error) ? error : BUS_PROBE_DEFAULT);
   }
   
   int
   uart_bus_attach(device_t dev)
   {
           struct uart_softc *sc, *sc0;
           const char *sep;
           int error;
   
           /*
            * The sc_class field defines the type of UART we're going to work
            * with and thus the size of the softc. Replace the generic softc
            * with one that matches the UART now that we're certain we handle
            * the device.
            */
           sc0 = device_get_softc(dev);
           if (sc0->sc_class->size > sizeof(*sc)) {
                   sc = malloc(sc0->sc_class->size, M_UART, M_WAITOK|M_ZERO);
                   bcopy(sc0, sc, sizeof(*sc));
                   device_set_softc(dev, sc);
           } else
                   sc = sc0;
   
           /*
            * Protect ourselves against interrupts while we're not completely
            * finished attaching and initializing. We don't expect interrupts
            * until after UART_ATTACH() though.
            */
           sc->sc_leaving = 1;
   
           mtx_init(&sc->sc_hwmtx_s, "uart_hwmtx", NULL, MTX_SPIN);
           if (sc->sc_hwmtx == NULL)
                   sc->sc_hwmtx = &sc->sc_hwmtx_s;
   
           /*
            * Re-allocate. We expect that the softc contains the information
            * collected by uart_bus_probe() intact.
            */
           sc->sc_rres = bus_alloc_resource(dev, sc->sc_rtype, &sc->sc_rrid,
               0, ~0, uart_getrange(sc->sc_class), RF_ACTIVE);
           if (sc->sc_rres == NULL) {
                   mtx_destroy(&sc->sc_hwmtx_s);
                   return (ENXIO);
           }
           sc->sc_bas.bsh = rman_get_bushandle(sc->sc_rres);
           sc->sc_bas.bst = rman_get_bustag(sc->sc_rres);
   
           sc->sc_irid = 0;
           sc->sc_ires = bus_alloc_resource_any(dev, SYS_RES_IRQ, &sc->sc_irid,
               RF_ACTIVE | RF_SHAREABLE);
           if (sc->sc_ires != NULL) {
                   error = bus_setup_intr(dev,
                       sc->sc_ires, INTR_TYPE_TTY, 
                       uart_intr, NULL, sc, &sc->sc_icookie);                  
                   if (error)
                           error = bus_setup_intr(dev,
                               sc->sc_ires, INTR_TYPE_TTY | INTR_MPSAFE,
                               NULL, (driver_intr_t *)uart_intr, sc, &sc->sc_icookie);
                   else
                           sc->sc_fastintr = 1;
   
                   if (error) {
                           device_printf(dev, "could not activate interrupt\n");
                           bus_release_resource(dev, SYS_RES_IRQ, sc->sc_irid,
                               sc->sc_ires);
                           sc->sc_ires = NULL;
                   }
           }
           if (sc->sc_ires == NULL) {
                   /* XXX no interrupt resource. Force polled mode. */
                   sc->sc_polled = 1;
           }
   
           sc->sc_rxbufsz = 384;
           sc->sc_rxbuf = malloc(sc->sc_rxbufsz * sizeof(*sc->sc_rxbuf),
               M_UART, M_WAITOK);
           sc->sc_txbuf = malloc(sc->sc_txfifosz * sizeof(*sc->sc_txbuf),
               M_UART, M_WAITOK);
   
           error = UART_ATTACH(sc);
           if (error)
                   goto fail;
   
           if (sc->sc_hwiflow || sc->sc_hwoflow) {
                   sep = "";
                   device_print_prettyname(dev);
                   if (sc->sc_hwiflow) {
                           printf("%sRTS iflow", sep);
                           sep = ", ";
                   }
                   if (sc->sc_hwoflow) {
                           printf("%sCTS oflow", sep);
                           sep = ", ";
                   }
                   printf("\n");
           }
   
           if (bootverbose && (sc->sc_fastintr || sc->sc_polled)) {
                   sep = "";
                   device_print_prettyname(dev);
                   if (sc->sc_fastintr) {
                           printf("%sfast interrupt", sep);
                           sep = ", ";
                   }
                   if (sc->sc_polled) {
                           printf("%spolled mode", sep);
                           sep = ", ";
                   }
                   printf("\n");
           }
   
           if (sc->sc_sysdev != NULL) {
                   if (sc->sc_sysdev->baudrate == 0) {
                           if (UART_IOCTL(sc, UART_IOCTL_BAUD,
                               (intptr_t)&sc->sc_sysdev->baudrate) != 0)
                                   sc->sc_sysdev->baudrate = -1;
                   }
                   switch (sc->sc_sysdev->type) {
                   case UART_DEV_CONSOLE:
                           device_printf(dev, "console");
                           break;
                   case UART_DEV_DBGPORT:
                           device_printf(dev, "debug port");
                           break;
                   case UART_DEV_KEYBOARD:
                           device_printf(dev, "keyboard");
                           break;
                   default:
                           device_printf(dev, "unknown system device");
                           break;
                   }
                   printf(" (%d,%c,%d,%d)\n", sc->sc_sysdev->baudrate,
                       "noems"[sc->sc_sysdev->parity], sc->sc_sysdev->databits,
                       sc->sc_sysdev->stopbits);
           }
   
           sc->sc_pps.ppscap = PPS_CAPTUREBOTH;
           pps_init(&sc->sc_pps);
   
           error = (sc->sc_sysdev != NULL && sc->sc_sysdev->attach != NULL)
               ? (*sc->sc_sysdev->attach)(sc) : uart_tty_attach(sc);
           if (error)
                   goto fail;
   
           if (sc->sc_sysdev != NULL)
                   sc->sc_sysdev->hwmtx = sc->sc_hwmtx;
   
           sc->sc_leaving = 0;
           uart_intr(sc);
           return (0);
   
    fail:
           free(sc->sc_txbuf, M_UART);
           free(sc->sc_rxbuf, M_UART);
   
           if (sc->sc_ires != NULL) {
                   bus_teardown_intr(dev, sc->sc_ires, sc->sc_icookie);
                   bus_release_resource(dev, SYS_RES_IRQ, sc->sc_irid,
                       sc->sc_ires);
           }
           bus_release_resource(dev, sc->sc_rtype, sc->sc_rrid, sc->sc_rres);
   
           mtx_destroy(&sc->sc_hwmtx_s);
   
           return (error);
   }
   
   int
   uart_bus_detach(device_t dev)
   {
           struct uart_softc *sc;
   
           sc = device_get_softc(dev);
   
           sc->sc_leaving = 1;
   
           if (sc->sc_sysdev != NULL)
                   sc->sc_sysdev->hwmtx = NULL;
   
           UART_DETACH(sc);
   
           if (sc->sc_sysdev != NULL && sc->sc_sysdev->detach != NULL)
                   (*sc->sc_sysdev->detach)(sc);
           else
                   uart_tty_detach(sc);
   
           free(sc->sc_txbuf, M_UART);
           free(sc->sc_rxbuf, M_UART);
   
           if (sc->sc_ires != NULL) {
                   bus_teardown_intr(dev, sc->sc_ires, sc->sc_icookie);
                   bus_release_resource(dev, SYS_RES_IRQ, sc->sc_irid,
                       sc->sc_ires);
           }
           bus_release_resource(dev, sc->sc_rtype, sc->sc_rrid, sc->sc_rres);
   
           mtx_destroy(&sc->sc_hwmtx_s);
   
           if (sc->sc_class->size > sizeof(*sc)) {
                   device_set_softc(dev, NULL);
                   free(sc, M_UART);
           } else
                   device_set_softc(dev, NULL);
   
           return (0);
   }

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